A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In such a case, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. including part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Conventional lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.
In current lithographic apparatus, one or more movable parts of the apparatus may be provided with a gas (e.g., air) bearing. In order to provide such a gas bearing with pressurized gas, a movable part which travels a relatively long distance typically has a flexible gas supply cable loop connected thereto.
However, the cable loop can consume significant design space and may cause disturbance forces towards one or more components attached to the cable loop. This may disturb the critical process of lithographic manufacture. Furthermore, the gas supply cable loop may have a limited lifetime.
For a movable part that moves a relatively short distance, a supply groove may be made in a track used to guide the movable part, and thus avoid use of a gas supply cable loop. For relatively long travel distances, this may not be possible.